1. Field of the Invention
The present invention relates to a sheet processing apparatus and an image forming system.
2. Description of the Related Art
In recent years, there is known a sheet processing apparatus that is connected and used with an image forming apparatus as a part of an image forming system and that binds a plurality of image-formed sheets output by the image forming apparatus.
As the sheet processing apparatus as described above, a sheet processing apparatus has been proposed, which includes a staple binding unit that performs a binding process by a binding method using a staple (hereinafter, referred to as “staple binding”) and a stapleless binding unit that performs a binding process by a binding method without using a staple (hereinafter, referred to as “stapleless binding”) (for example, see Japanese Unexamined Patent Publication No. 2012-148505).
The sheet processing apparatus configured as described above, upon accepting a binding process execution request, moves a specified binding unit to a binding position without waiting for image formation and output performed by the image forming apparatus to complete. This is done to improve productivity by immediately performing a binding process when all of sheets to be bound are obtained.
Furthermore, in the above-described sheet processing apparatus, an upper limit of the number of sheets that can be bound at one time by the stapleless binding unit (hereinafter, referred to as the “number of bindable sheets”) is generally lower than that of the staple binding unit.
Therefore, when a stapleless binding execution request is accepted, and if the specified number of to-be-bound sheets exceeds the number of bindable sheets of the stapleless binding unit, the above-described sheet processing apparatus becomes unable to perform a binding process. Therefore, a sheet processing apparatus has been proposed, which automatically switches from the stapleless binding to the staple binding in the above-described case (for example, see Japanese Unexamined Patent Publication No. 2013-170067).
However, when the above-described sheet processing apparatus switches from the stapleless binding to the staple binding, it is necessary to move the staple binding unit from a home position to a binding position, so that the productivity of the binding process is reduced accordingly.